We formulate the counting task as a density map estimation problem [1]}. The density (intensity) of each pixel in the map depends on its proximity to a vehicle centroid and the size of the vehicle in the image so that each vehicle contributes with a total value of 1 to the map. Therefore, it provides statistical information about the location of the vehicles and allows the counting to be estimated by summing all density values (see also sec:back:visual-counting:traditional-approaches.)
